South Korea has proposed a broad range of economic aid for impoverished North Korea if it agrees to give up its nuclear programme.
It was not immediately clear how the North would respond to the proposal.
However, it has repeatedly rejected the idea of abandoning its nuclear programme, which it says is a necessary deterrent against US hostility.
North and South Korea have been technically at war since the end of their 1950-53 civil conflict, as the fighting ended with a mere truce and not a treaty.
North Korea threatened nuclear strikes against the South and the United States last year, after the United Nations tightened sanctions against it for conducting its third nuclear test.
South Korean President Park Geun-hye said the two Koreas must put confrontation behind them and start the work of preparing for unification.
She offered to help develop the North's economy, agriculture and social infrastructure.
"In order for these efforts for us to become one again to bear results at an early time, North Korea must go on the road to denuclearisation," Ms Park said.
She also offered to help the North join the international financial system and proposed the establishment of liaison offices on both sides to promote exchanges.
The proposal continues a series of policy initiatives by Ms Park and her predecessor, offering huge economic incentives in return for the North giving up its nuclear ambitions.
Five countries, including the South and the US, also struck a deal in 2005 with the North to provide economic aid in return for an agreement to end its nuclear arms programme, which the North has since torn up.
Yesterday, the North ridiculed Ms Park in scathing commentary for her comments at a nuclear security summit earlier in the week in The Hague, where she spoke about the risk of nuclear weapons proliferation posed by North Korea.
"Explicitly speaking about the nuclear issue, there may be the denuclearisation of the whole Korean peninsula but no unilateral denuclearisation by the north under any circumstances," it said.
"She had better not even dream about it."
North Korea has accused the US of maintaining nuclear weapons in South Korea and planning to invade the North, which the US denies.
North Korea's economy is about a thirtieth of the size of industrial powerhouse South Korea and it often has trouble feeding its people.
Its missile launches and nuclear tests since 2006 have led to UN Security Council resolutions that ban arms trade and cut it off international financial system.
In the latest rebuke of the North's arms provocation, the UN Security Council condemned its ballistic missile launch this week as a violation of resolutions and said it would hold discussions on a response.